The present disclosure relates to lubrication oil tanks for gas turbine engines used in aircraft.
An oil tank for a gas turbine engine is generally serviced and filled by a ground cart equipped with a pressure fill system and/or manually with cans of oil. In some aircraft, the oil tank is mounted on the turbine engine where the ground cart cannot easily access and refill the oil tank. In this situation, the oil tank on the turbine engine is plumbed to a fill fitting and an overfill fitting on the bulkhead of the aircraft where access is easier for the ground cart.
During a servicing event, the pressure fill system of the ground cart is connected to both the fill fitting and the overfill fitting on the bulkhead. The fill fitting generally includes a check valve that is automatically opened as the pressure fill system directs pressurized oil into the fill fitting. The overfill fitting generally includes a mechanical valve that is opened by the act of connecting the pressure fill system to the overflow fitting. With the valves open, the pressure fill system of the ground cart sends pressurized oil to the oil tank. Overfilling the oil tank can cause harm to the working parts of the turbine engine. To prevent the oil tank from overfilling, excess oil inside the oil tank is returned to the pressure fill system via the overfill fitting.
After the oil tank is filled, the pressure fill system is disconnected from the fill fitting and the overfill fitting. Engine damage or failure can also result should either of the valves in the fill fitting or the overfill fitting fail during engine operation. In the case where the fill and overfill fittings are mounted to the bulkhead of the aircraft, engine damage or failure can also occur should the plumbing to the engine fail and leak oil during operation.